Valves are used for controlling the motion of liquids or gases in piping or the like as may be desired. In classifying such valves, one important point is for example the number of connections such valves have. For example a three-way valve is a valve with three connections, that is to say an inlet connection (P), a connection (A) for joining with a cylinder and piston actuator and an outlet or left off connection (R). A five-way valve has five connections, that is to say an inlet connection (P), two cylinder actuator connections (A,B) and two outlet connections (R, S), such valves being used for example for the operation of double-acting piston cylinder actuators. Operation of the valve, that is to say putting it into the desired condition of switching from the outside, may be undertaken in a number of different ways, for example by hand, this being the simplest case, mechanically (using for example a cam) or by air power (using for example compressed air) or control may be electrical using a timer. So it will be seen that there is a large number of different sorts of valves which may be put into different groups dependent on the number of connections, the number of positions or settings and the way of operation.